Such gas generators have been known (cf. U.S. Pat. No. 4,561,675 and DE 39,14,690 A1). At ambient temperatures of about 150.degree. to 200.degree. C., which may occur, e.g., in the case of a fire, the spontaneous ignition agent leads to ignition of the propellant and thus to release of the air bag. The generator housing, which consists, in general, of aluminum or another similar lightweight material, still has sufficient strength at these temperatures. Fragmentation of the housing during the release of the air bag in the case of fire is thus prevented.
According to U.S. Pat. No. 4,561,675 and DE 39,14,690 A1, gun powder, i.e., nitrocellulose, is used as the spontaneous ignition agent, possibly in conjunction with other organic nitro compounds.
An air bag gas generator, including the spontaneous ignition agent, is required to remain able to function over a period of 400 hours under a temperature load of up to 110.degree. C. Such peak temperatures may occur, e.g., during prolonged exposure to direct sunlight. However, nitrocellulose is decomposed during prolonged heating. The requirement is therefore not met by the prior-art spontaneous ignition agents.